Risers are typically assembled on a stage for choral presentations. Due to the multiple uses to which the staging area is put, the need for the risers is generally only for the duration of the choral presentation. Accordingly, it is desirable that such risers are easily set up in a sturdy, operational configuration suitable for delivering a choral presentation. Additionally, such risers must also be easily disassembled and stored in the minimal amount of space possible. The risers should be easily movable from the stage area to a remote storage area through normal sized doorways. Further, when assembling a stage presentation form using a plurality portable risers, it is desirable to have the flexibility to utilize the portable risers to define a plurality of stage presentation forms, such as for example, a presentation form that has a straight center portion with inward curved end portions, a straight presentation form, or a curved presentation form.
Examples of existing designs of foldable staging devices include the telescoping platform structure depicted in U.S. Pat. No. 3,400,502 to R. T. Schaggs et al. U.S. Pat. No. 5,050,353 to Rogers et al. depicts a riser in which the frame is interconnected by collapsible gates that permit the entire frame to collapse for storage. U.S. Pat. No. Des. 307,186 to Rogers et al. depicts a hinged three tier riser in which the entire tier of steps may be raised to a stowed position. U.S. Pat. No. 3,747,706 to Paine et al. depicts a collapsible riser in which both the steps and the guard rail collapse and the entire apparatus is tipped on end for transport to a storage area. U.S. Pat. No. Re. 30,830 to Wenger et al. depicts a portable riser that collapses from an erect operational configuration to a stowed configuration using a bilateral folding action. U.S. Pat. No. 4,979,340 to Wilson et al. depicts a folding riser having a main frame that supports the guard rail and secondary frame that supports the steps, wherein the secondary frame is foldable onto the primary frame for storage.
While the above examples of prior staging devices have certain merits, the requirement for a sturdy, simple, easily collapsible, and compact riser that includes the flexibility of quickly changing the presentation form has been the focus of continuing industry efforts.